#include <iostream>

void use_variable() {
    int a = 5, b = 10;
    int sum = a + b;
    std::cout << "the sum of " << a << " and " << b << " is " << sum << std::endl;
}

void use_cout() {
    std::cout << "hello world" << std::endl;

    int num = 42;
    std::cout << num << std::endl;

    double pi = 3.141592;
    std::cout << pi << std::endl;

    char ch = 'A';
    std::cout << ch << std::endl;

    bool truth = true;
    std::cout << std::boolalpha;
    std::cout << truth << std::endl;
}

void practice() {
    double pai_val = 3.14;
    int val = 5;
    std::cout << pai_val << " " << val << std::endl;

    bool flag = -100;
    std::cout << std::boolalpha << flag << std::endl;
}

int main() {
    //use_variable();
    //use_cout();
    practice();

    return 0;
}